1. Field of the Invention
The present invention relates to a method for processing the images of the human brain, and more particularly to a method for segmenting and calculating the volume of the white matter, the gray matter, and the cerebral spinal fluid (CSF) in a human brain using images produced by a magnetic resonance (MR) imaging device.
2. Description of the Related Art
Medical research into the structure and operation of the human brain has been extensive, and there have been remarkable advances in medical procedures used for the discovery and cure of various cerebral diseases. In particular, the use of computed tomography (CT) and magnetic resonance (MR) imaging have been particularly useful as diagnostic tools and it is expected that the use of such images will continue into the future.
Certain degenerative cerebral diseases, such as Alzheimer's disease and cerebral palsy, involve the atrophy of the brain, and CT and/or MR images have shown to be useful in diagnosing such diseases. However, this assessment typically relies on the subjective judgment of the radiologist who visually scrutinizes such images by the naked eye. Unfortunately, there has not yet been developed a method for early diagnosis of such diseases using objective criteria involving the quantitative measurement of tissue atrophy of the white and gray matters in the brain and the resultant increase of cerebral spinal fluid (CSF).
Since the atrophy of the white and gray matters and the accompanying increase of the cerebral spinal fluid are the most common phenomena observed in patients with degenerative cerebral diseases, a quantitative calculation of the degree of atrophy in suspect tissues, monitoring the change of their volumes, and comparison of them with those of normal unaffected persons, could greatly improve the diagnosis of such diseases.
However, the complexity of the human brain and peculiarities of MR images make such a calculation difficult. Specifically, a particular voxel (i.e., the smallest until of volume resolvable in the image) is assigned one particular intensity value (i.e., a gray scale value) in the MR image, but may in fact contain partial volumes of white matter, gray matter, or CSF, giving rise to a “blurring” of the image. A method has not as yet been implemented for segmenting the respective portions of the white matter, the gray matter, and the CSF from each other in a given voxel, and hence the problem of blurring remains. This prevents the ability to accurately calculate the volume of the white matter, the gray matter, and the cerebral spinal fluid.
To date, some researchers have attempted to segment white and gray matter using T1-weighted images by semi-automatic means through manual interaction with the computer interface connected to the MR machine. However, T1-weighted images do not provide a good contrast between white and gray matter, and do not allow for a separate assessment of CSF. Additionally, the time, expense, and uncertainty of manually manipulating the MR images in this fashion makes this technique undesirable.